U.S. patent number 5,994,415 [Application Number 09/078,958] was granted by the patent office on 1999-11-30 for compound antifoams for defoaming polymer dispersions and aqueous coating systems.
This patent grant is currently assigned to Th. Goldschmidt AG. Invention is credited to Burghard Gruning, Petra Hinrichs, Michael Keup, Frank Konig, Stefan Silber, Roland Sucker, Ellen Wallhorn.
United States Patent |
5,994,415 |
Gruning , et al. |
November 30, 1999 |
Compound antifoams for defoaming polymer dispersions and aqueous
coating systems
Abstract
The invention relates to compound antifoams comprising
alkoxylated partial esters--using from 3 to 60 mol of propylene
oxide with or without from 1 to 10 mol of styrene oxide and/or from
1 to 10 mol of butylene oxide--of oligoglycerols, obtainable by
condensation of 2 to 20 glycerol molecules, with C.sub.8 to
C.sub.22 fatty acids and inorganic or organic solids for defoaming
polymer dispersions and aqueous coating systems.
Inventors: |
Gruning; Burghard (Essen,
DE), Hinrichs; Petra (Bochum, DE), Keup;
Michael (Essen, DE), Konig; Frank (Gelsenkirchen,
DE), Silber; Stefan (Krefeld, DE), Sucker;
Roland (Werne, DE), Wallhorn; Ellen (Essen,
DE) |
Assignee: |
Th. Goldschmidt AG (Essen,
DE)
|
Family
ID: |
7829861 |
Appl.
No.: |
09/078,958 |
Filed: |
May 14, 1998 |
Foreign Application Priority Data
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May 17, 1997 [DE] |
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197 20 870 |
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Current U.S.
Class: |
516/116; 516/133;
524/290; 524/291; 524/320 |
Current CPC
Class: |
B01D
19/0404 (20130101); B01D 19/0404 (20130101); B01D
19/0413 (20130101); B01D 19/0404 (20130101); B01D
19/0409 (20130101) |
Current International
Class: |
B01D
19/02 (20060101); B01D 19/04 (20060101); C09K
3/00 (20060101); B01D 019/04 () |
Field of
Search: |
;516/116,133
;524/290,291,320 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1067003 |
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Mar 1960 |
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DE |
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1914684 |
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Dec 1970 |
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DE |
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3636086 A1 |
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Apr 1988 |
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DE |
|
Primary Examiner: Lovering; Richard D.
Assistant Examiner: Metzmaier; Daniel S.
Attorney, Agent or Firm: Frommer Lawrence & Haug LLP
Claims
What is claimed is:
1. An antifoam formulation for defoaming polymer dispersions and
aqueous coating systems, comprising
a) about 85.0 to about 99.9 parts by weight of an alkoxylated
partial ester of an oligo-glycerol which was esterified with
C.sub.8 to C.sub.22 fatty acids and alkoxylated with about 3 to
about 60 mol of propylene oxide and optionally with about 1 to
about 10 mol of styrene oxide optionally about 1 to about 10 mol of
butylene oxide, and
b) about 0.1 to about 15.0 parts by weight of an inorganic or
organic solid.
2. A formulation as claimed in claim 1, wherein the partial esters
are formed from the esterification of oligoglycerols, obtained by
the condensation of 3 to 8 glycerol molecules, with C.sub.8 to
C.sub.22 fatty acids.
3. The formulation as claimed in claim 2, wherein the partial
esters are formed from the esterification of oligoglycerols,
obtained by the condensation of 4 to 6 glycerol molecules with
caprylic, capric, laurylic, myristic, palmitic, stearic, isosteric,
oleric, ricnoleric and 12-hydroxysteric acid.
4. A formulation as claimed in claim 1, wherein the alkoxylated
partial ester is alkoxylated with about 10 to about 30 mol of
propylene oxide and about 1 to about 10 mol of styrene oxide and
about 1 to about 10 mol of butylene oxide.
5. A formulation as claimed in claim 1, wherein the alkoxylated
partial ester of an oligoglycerol is obtained by the alkoxylation
product of triglycerol trilaurate, 30 mol of propylene oxide, and 3
mol of butylene oxide.
6. A formulation as claimed in claim 1, wherein the alkoxylated
partial ester of an oligoglycerol is obtained by the alkoxylation
product of pentaglycerol pentoleate, 50 mol of propylene oxide and
5 mol of butylene oxide.
7. A formulation as claimed in claim 1, wherein the alkoxylated
partial ester of an oligoglycerol is obtained by the alkoxylation
product of pentaglycerol pentalaurate, 50 mol of propylene oxide
and 5 mol of styrene oxide.
8. An aqueous emulsion which comprises the antifoam formulation
according to claim 1.
9. The emulsion according to claim 8, wherein the average droplet
size of the emulsion lies between about 1 and about 10 .mu.m.
10. An aqueous emulsion which comprises the antifoam formulation
according to claim 1, wherein the partial esters in said
formulation are formed from the esterification of oligoglycerols,
obtained by the condensation of 3 to 8 glycerol molecules, with
C.sub.8 to C.sub.22 fatty acids.
11. An aqueous formulation which comprises about 5 to about 50% of
the formulation according to claim 1.
12. An antifoam formulation for defoaming polymer dispersions and
aqueous coating systems, comprising
a) 85.0 to 99.9 parts by weight of an alkoxylated partial ester of
an oligo-glycerol which was esterified with C.sub.8 to C.sub.22
fatty acids and alkoxylated with 3 to 60 mol of propylene oxide and
optionally with 1 to 10 mol of styrene oxide and optionally 1 to 10
mol of butylene oxide, and
b) 0.1 to 15.0 parts by weight of an inorganic or organic solid.
Description
RELATED APPLICATIONS
This application claims priority to German application No. 197 20
870.3, filed May 17, 1997, herein incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to compound antifoams comprising alkoxylated
partial esters of oligoglycerols, obtainable by condensation of 2
to 20 glycerol molecules, with C.sub.8 to C.sub.22 fatty acids and
inorganic or organic solids for defoaming polymer dispersions and
aqueous coating systems.
2. Description of the Related Art
In many industrial processes, surface-active substances are
employed in a targeted manner in order to obtain particular
effects. For instance, aqueous coating materials require a range of
auxiliaries, examples including emulsifiers to emulsify the
water-insoluble binders, or additives to improve substrate wetting
and pigment dispersion. An undesirable side effect of these
surface-active substances, however, is that they stabilize, in the
form of foam, the air introduced in the course of preparation or
application.
The use of silicone oils, especially dimethylpolysiloxanes of low
to medium viscosity, for defoaming aqueous solutions or dispersions
is known and is described, for example, in the book by W. Noll
"Chemie und Technologie der Silicone" [Chemistry and Technology of
the Silicones]. To improve the defoaming action of organosilicon
antifoams and/or those based on mineral oil it is common to add
highly disperse inorganic or organic substances, especially silicas
produced generally by the pyrogenic method (DE-C-10 67 003, DE-A-19
14 684). The use of polyoxyalkylene-polysiloxane copolymers as
antifoams is likewise known (U.S. Pat. No. 3,763,021).
These prior art formulations comprising silicone oils or
polyoxyalkylene-polysiloxane copolymers are suitable to a greater
or lesser extent for preventing the formation of foam in polymer
dispersions or aqueous coating systems or for destroying existing
foam. It has been found, however, that aqueous coating systems to
which formulations of this kind have been added have disadvantages
which are attributable to the addition of these antifoams.
It has been found in particular that high-gloss emulsion paints to
which polysiloxanes, polyoxyalkylene-polysiloxane copolymers or
formulations based on mineral oil have been added to remove foam,
exhibit a variety of wetting defects, and also reduce gloss, when
they are applied to surfaces. These defects are manifested in
nonuniform wetting of the substrate, and lead to the formation of
coatings of irregular thickness and, in extreme cases, to coatings
containing defect sites of varying extent.
Moreover, the use of silicone-based products in aqueous coating
systems often provokes problems of interlayer adhesion; when used
in dipping tanks, it is difficult to avoid the occurrence of
craters over a prolonged period; and, in application processes that
are followed by catalytic post-combustion, the service life of the
catalysts is reduced.
In addition, the use of products based on mineral oil is in many
cases inopportune. In addition to the physiological and ecological
risks, these carrier oils reduce--in aqueous media, for
example--the degree of gloss of emulsion paints or lead, in
flexographic printing inks, to unwanted swelling of the
flexographic plates.
DE-A-36 36 086 describes fatty acid esters of polyglycerol
polyglycol ethers that are obtained by conventional reaction of
polyglycerols with ethylene oxide and propylene oxide and by
esterifying the resulting alkylene oxide adduct with fatty acids,
using from 2 to 15 mol of ethylene oxide, from 10 to 60 mol of
propylene oxide and from 1 to 3 mol of fatty acid per mole of
hydroxyl groups present in the polyglycerol. In aqueous coating
systems, however, the foam prevention properties of these products
are inadequate because it is not possible to obtain the necessary
long-term action in the paint.
OBJECT OF THE INVENTION
The object on which the present invention is based, therefore, is
to discover suitable antifoam formulations which are free from
silicone and mineral oil, which exhibit a good defoaming action in
polymer dispersions and in aqueous coating systems comprising such
dispersions, which retain this effect over a relatively long time,
but which at the same time avoid the problems described above.
SUMMARY OF THE INVENTION
This object on which the invention is based is surprisingly
achieved by the use of alkoxylated partial esters of
oligoglycerols, obtainable by condensation of from 2 to 20 glycerol
molecules, with C.sub.8 to C.sub.22 fatty acids, and compound
formulations prepared therefrom, using from about 3 to about 60 mol
of propylene oxide and preferably from about 1 to about 10 mol of
styrene oxide and/or from about 1 to about 10 mol of butylene
oxide.
An important feature of these systems when used as antifoams in
aqueous coating systems is that one avoids using hydrophilic
polyethylene oxide segments and compounding the esters with organic
and/or inorganic, preferably hydrophobic solids.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Partial esters of fatty acids with oligoglycerols obtainable by
condensation of from 2 to 20 glycerol molecules are known (DE-C-25
11 807 which corresponds to U.S. Pat. No. 5,336,313). These partial
esters are commonly employed as internal lubricants and/or as
antistatic polymer additives. Their use as a dispersing additive in
aqueous coating dispersions has also been described (EP-B-0 479 819
which corresponds to U.S. Pat. No. 4,011,251).
The partial esters to be employed in accordance with the invention
are prepared from an alcohol component comprising oligoglycerols
obtainable by condensing from 2 to 20 glycerol molecules,
preference being given to oligoglycerols composed formally of from
2 to 10, in particular from 4 to 6, glycerol units in preparing the
partial esters. It is also possible to employ technical-grade
mixtures of the oligoglycerols having the stated chain lengths.
Oligoglycerols obtainable by other methods are also suitable for
preparing the partial esters.
To prepare the partial esters that are to be employed in accordance
with the invention, such oligoglycerols are partially esterified
with C.sub.8 to C.sub.22 fatty acids, leaving preferably one to two
hydroxyl groups unmodified in the oligoglycerol moiety. As examples
of C.sub.8 to C.sub.22 fatty acids there may be mentioned caprylic,
capric, laurylic, myristic, palmitic, stearic, isostearic, oleic,
ricinoleic and 12-hydroxystearic acids. Also suitable are dihydroxy
acids or dimeric acids. For preparing the partial esters the fatty
acids can usually be employed in the form of their technical-grade
mixtures.
The partial esters, which still contain free hydroxyl groups,
obtainable in this way can be modified by addition reaction with
alkylene oxides, such as propylene oxide, styrene oxide and
butylene oxide. It is possible to add the various alkylene oxides
randomly or in blocks. Particular preference is given to the
addition of about 3 to about 60 mol of propylene oxide, especially
about 10 to about 30 mol of propylene oxide, and about 1 to about
10 mol of styrene oxide and/or about 1 to about 10 mol of butylene
oxide.
The partial esters to be used in accordance with the invention also
comprise products obtainable by first alkoxylating the parent
oligoglycerol starting materials and then carrying out the
esterification with appropriate fatty acids. The reaction
conditions for etherification and esterification are those of the
prior art. Catalysts suitable for the etherification include both
acidic and basic catalysts, with preference to potassium hydroxide,
potassium methylate, sodium methylate or BF.sub.3 etherate. The use
of BF.sub.3 etherate is particularly preferred.
One skilled in the art is well aware that the compounds are present
in the form of a mixture with a distribution governed essentially
by the laws of statistics.
The compound formulations that are to be used in accordance with
the invention for defoaming polymer dispersions and aqueous coating
systems comprising:
a) about 85.0 to about 99.9 parts by weight of an alkoxylated
partial ester of an oligo-glycerol which has esterified with
C.sub.8 to C.sub.22 fatty acids, and alkokylated with about 3 to
about 60 mol of propylene oxide and, optionally about 1 to about 10
mol of styrene oxide and/or about 1 to about 10 mol of butylene
oxide,
b) about 0.1 to about 15.0 parts by weight of an inorganic or
organic solid.
Examples of inorganic solids are unmodified or hydrophobicized
silicas, metal soaps, alumina, alkaline earth metal carbonates, or
similar, customary, finely divided solids known from the prior art.
As finely divided organic substances it is possible to use alkaline
earth metal salts of long-chain fatty acids of 12 to 22 carbon
atoms that are known for this purpose, the amides of these acids,
micronized waxes, or oligoureas produced in situ.
The formulations of the invention are used as they are or in the
form of aqueous emulsions. The use of emulsions is preferred
because of the better metering options. Particular preference is
given to antifoam emulsions whose average particle size lies
between about 1 and about 10 .mu.m. Aqueous emulsions with a
content of about 5 to about 50% of the formulations of the
invention are particularly preferred.
The compound formulations of the invention are added to the polymer
dispersions and aqueous coating systems in amounts of about 0.01 to
about 3% by weight.
EXAMPLES
Examples of partial esters of oligoglycerides that are in
accordance with the invention and are particularly suitable in the
compound antifoams are:
a) The alkoxylation product of triglycerol trilaurate+30 mol of
propylene oxide+3 mol of styrene oxide+3 mol of butylene oxide
b) The alkoxylation product of pentaglycerol pentaoleate+50 mol of
propylene oxide+5 mol of butylene oxide
c) The alkoxylation product of pentaglycerol pentalaurate+50 mol of
propylene oxide+5 mol of styrene oxide
Compounds that are not in accordance with the invention but were
investigated for purposes of comparison are:
d) The alkoxylation product of triglycerol trioleate+20 mol of
propylene oxide+20 mol of ethylene oxide
e) The alkoxylation product of pentaglycerol pentaoleate+30 mol of
propylene oxide+5 mol of ethylene oxide
f) Triglycerol triacetate
g) Polypropylene glycol comprising 50 mol of propylene oxide.
These compounds in accordance and not in accordance with the
invention are formulated with 3% of Sipernat D10 (hydrophobic
silica from Degussa) in each case to give the respective compound
antifoams A to G.
The text below indicates the performance properties of the various
compound formulations of the invention and of the Comparative
Examples.
The performance properties were tested in two commercially
available polymer dispersions, an emulsion paint, and a water-based
flexographic printing ink.
The test systems selected were as follows:
a. Styrene acrylate dispersion Acronal 290 D, from BASF
b. All-acrylate dispersion Acronal A603, from BASF
c. An emulsion paint is formulated conventionally to the recipe
below (amounts in % by weight):
______________________________________ Propylene glycol 4.8
Collacral AS35 5.0 BASF, wetting and dispersing agent Titanium
dioxide 23.2 Mergal K7 0.2 Riedel de Haen, preservative Butyl
glycol 2.6 Dowanol DPM 1.4 Water 6.9 Acronal A603 54.3 BASF,
all-acrylate dispersion Rheolate 278 4.0 Rheox, thickener
______________________________________
d. A flexographic printing ink is formulated conventionally to the
following recipe (amounts in % by weight):
Millbase:
______________________________________ Joncryl 81 18.7 acrylate
resin solution, Johnson- Polymer Foamex 840 0.1 antifoam, Tego
Chemie Service Water 7.5 Heliogenblau D7080 11.2 phthalocyanine
blue, BASF 1 hour of dispersing (Apparatus: Scandex) Make-up
mixture: Joncryl 8051 46.2 acrylate dispersion, Johnson- Polymer
Jonwax 35 4.7 polyethylene wax emulsion, Johnson- Polymer Water 6.8
Isopropanol 4.7 ______________________________________
5 minutes of dispersing (Apparatus: Scandex)
As the last constituent of the recipe, 0.2% of the compound
antifoams according and not according to the invention is added in
each case and incorporated at 1000 rpm for one minute.
Foam test (for a. and b.)
By dispersion for 1 minute at 2,500 rpm using a turbine agitator
(diameter 4 cm), air is incorporated into the polymer dispersions
treated with 0.2% by weight of compound antifoam additive. Then,
directly after the agitator has been shut off, the resulting
dispersion is introduced into a measuring cylinder up to the 50 ml
calibration mark, and is weighed. The weight is influenced by the
amount of air incorporated by dispersion, and is a measure of the
efficacy of the antifoam.
Foam test (for d.)
50 g of the aqueous flexographic printing ink, treated with 0.2% by
weight of compound antifoam additive, are weighed out into a 150 ml
glass beaker and subjected to shearing at 2,500 rpm for one minute
using a dissolver disk (3 cm diameter). Then 45 g are weighed out
into an upright cylinder, and the foam height is indicated in
ml.
Roller test (for c.)
In the roller test, an open-pored foam roller is used to spread 40
g of the test emulsion paint onto a nonabsorbent test card with a
total area of 500 cm.sup.2. The foam roller is wetted with water
before the paint is applied. In this context it is ensured that the
same additional amount of water is introduced in each case into the
paint, so that the drying time of the paint remains the same in
each case. The wet film add-on is about 300 g/m.sup.2. After the
film has dried for 24 hours the test panels are evaluated in terms
of the macrofoam (number of bubbles per 100 cm.sup.2) and microfoam
(number of pinholes, by comparison with test panels having defect
patterns varying in their extent; scale from 1 (very good) to 5
(deficient, numerous pinholes)) present and for any wetting
defects.
The following results demonstrate the broad applicability of the
compound antifoams of the invention.
TABLE 1 ______________________________________ Foam test results
for styrene acrylate dispersion a Compound Concentration Sample
density .times. g/50 ml ______________________________________
Blank sample 0 39.2 A 0.2 49.7 B 0.2 49.8 C 0.2 50.1 D 0.2 47.6 E
0.2 46.2 F 0.2 39.6 F 0.5 40.1 G 0.2 44.3 G 0.5 48.2
______________________________________
TABLE 2 ______________________________________ Foam test results
for styrene acrylate dispersion b Compound Concentration Sample
density .times. g/50 ml ______________________________________
Blank sample 0 38 A 0.2 48.9 B 0.2 49.1 C 0.2 49.3 D 0.2 45.1 E 0.2
44.3 F 0.2 38.9 F 0.5 40.2 G 0.2 45.1 G 0.5 47.9
______________________________________
TABLE 3 ______________________________________ Roller test results
for emulsion paint c Wetting Compound Concentration Macrofoam
Microfoam defects ______________________________________ Blank
Sample 0 80 5 none A 0.2 0 1 none B 0.2 0 1 none C 0.2 0 1 none D
0.2 5 2 none E 0.2 7 3 slight F 0.2 72 5 none F 0.5 65 5 none G 0.2
10 2 none G 0.5 3 2 slight
______________________________________
TABLE 4 ______________________________________ Foam test results
for flexographic printing ink d Compound Concentration Foam level
in ml/45 g ______________________________________ Blank sample 0 62
A 0.2 46 B 0.2 47 C 0.2 45 D 0.2 52 E 0.2 50 F 0.2 62 F 0.5 65 G
0.2 53 G 0.5 49 ______________________________________
The above description of the invention is intended to be
illustrated and not limiting. Various changes or modifications in
the embodiments described may occur to those skilled in the art.
These can be made without departing from the spirit or scope of the
invention.
* * * * *